This invention is in the field of tissue engineering. The present invention is a resilient, biocompatible two- or three-layered tissue graft which can be engineered in flat sheets or in tubes with various luminal diameters and thicknesses. At least one layer is composed of collagen or a collagenous material. The present invention is gradually degraded and bioremodeled by the host""s cells which replace the implanted prosthesis and assume its shape.
Each year approximately 300,000 coronary bypass procedures are performed in the United States. The typical treatment for small diameter artery replacement has been for surgeons to use the patient""s own vessels, usually the saphenous vein from the leg. However, in many cases, the use of the patient""s own vessels is not practical because the veins are either damaged, diseased or are not available. In these cases, synthetic materials are used, but with unsatisfactory long-term results. It is still a continuing goal of researchers to develop prostheses which can successfully be used to replace or repair mammalian tissue, particularly blood vessels.
This invention is directed to a method for treating damaged or injured organs, particularly blood vessels, by replacing, or repairing, a section of the organ in a patient with a bioremodelable collagen graft prostheses. This prosthesis, when implanted into a mammalian host, undergoes controlled biodegradation accompanied by adequate living cell replacement, or neo-tissue formation, such that the original implanted prosthesis is bioremodeled by the host""s cells before it is digested by host enzymes. The prosthesis of this invention comprises at least two layers: (a) at least one layer is composed of collagen or a collagenous material; and (b) at least one layer is composed of material which provides structural stability, and is pliable, semi-permeable, and suturable. In the preferred embodiment of this invention, the two-layered prosthesis has an inner (luminal) layer which provides a smooth, thrombosis-resistant flow surface and an outer structural layer which provides structural stability, and is pliable, semi-permeable, and suturable. In another preferred embodiment of this invention the prosthesis has three layers: an inner (luminal) layer which acts as a smooth, thrombosis-resistant flow surface; a middle structural layer which provides structural stability, and is pliable, semi-permeable, and suturable; and, an outer (abluminal) layer. The outer layers of both the two-layer or the three-layer prosthesis add strength to the graft and allow the patient""s host cells to attach and grow into the graft thereby facilitating the bioremodeling.
The invention is also directed to methods for preparing bioremodelable two-or three-layer tubular blood vessel prostheses by (a) forming a tubular structural layer that is pliable, semi-permeable, and suturable; (b) forming an inner layer to act as a smooth flow surface comprising deposition of acid-extracted fibrillar collagen onto the luminal surface of said structural layer of step (a); and, (c) creating the lumen. The inner layer may also be treated with drugs for anti-thrombotic effect, such as heparin or other appropriate agent(s). The prosthesis is next implanted into a mammalian host where it undergoes controlled biodegradation accompanied by adequate living cell replacement, or neo-tissue formation, such that the original implanted prosthesis is bioremodeled by the host""s cells.